43 lines
1.0 KiB
Python
43 lines
1.0 KiB
Python
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#
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# These tests require gmpy and test the limits of the 32-bit build. The
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# limits of the 64-bit build are so large that they cannot be tested
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# on accessible hardware.
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#
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import sys
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from decimal import *
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from gmpy import mpz
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_PyHASH_MODULUS = sys.hash_info.modulus
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# hash values to use for positive and negative infinities, and nans
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_PyHASH_INF = sys.hash_info.inf
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_PyHASH_NAN = sys.hash_info.nan
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# _PyHASH_10INV is the inverse of 10 modulo the prime _PyHASH_MODULUS
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_PyHASH_10INV = pow(10, _PyHASH_MODULUS - 2, _PyHASH_MODULUS)
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def xhash(coeff, exp):
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sign = 1
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if coeff < 0:
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sign = -1
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coeff = -coeff
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if exp >= 0:
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exp_hash = pow(10, exp, _PyHASH_MODULUS)
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else:
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exp_hash = pow(_PyHASH_10INV, -exp, _PyHASH_MODULUS)
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hash_ = coeff * exp_hash % _PyHASH_MODULUS
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ans = hash_ if sign == 1 else -hash_
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return -2 if ans == -1 else ans
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x = mpz(10) ** 425000000 - 1
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coeff = int(x)
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d = Decimal('9' * 425000000 + 'e-849999999')
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h1 = xhash(coeff, -849999999)
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h2 = hash(d)
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assert h2 == h1
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